1. Field of the Invention
The present invention relates to a plating processing device. More particularly, the present invention relates to a plating processing device used for manufacturing electronic parts such as lead frames, semiconductor wafers and so forth.
2. Description of the Related Art
There is provided a plating process such as a gold plating process in which an inner lead of a lead frame or a terminal of a wiring board is plated with gold in the process of manufacturing a semiconductor device. Various plating methods are used in the plating process. For example, in the case of partially plating an object to be plated such as a lead frame, the lead frame is interposed between masks used for plating, and a plating solution is jetted out into a plating region of the object that is exposed from the masks so as to conduct plating on the object to be plated.
After the completion of plating, the object which has been plated is dipped in a recovery tank to recover plating components so that a plating solution adhering to the object can be removed. Next, the plating solution adhering to the surface of the object is washed away in a washing tank.
In the plating process in which electronic parts such as lead frames are plated, an expensive plating solution such as a gold plating solution is used in some cases. Therefore, it is effective to recover and recycle the plating solution. Further, it is necessary to wash the object after the completion of plating in order to prevent the plating solution remaining on the object from exerting a bad influence on a product.
Concerning the method of washing the object to be plated, the following methods are used. One method is described as follows. After a plating solution has been jetted out to a semiconductor wafer in the process of manufacturing the semiconductor wafer, pure water is jetted out from the plating solution jetting nozzle to the semiconductor wafer so as to wash the semiconductor wafer. Another method is described as follows. Nozzles for jetting pure water are arranged in the outer plating bath so as to wash the object to be plated. After washing, a waste solution is made to flow into the inner bathing bath or the outer plating bath. These methods are disclosed in the official gazettes of Japanese Unexamined Patent Publication Nos. 11-92949 and 2001-316878.
However, according to the above method in which the plating solution is recovered into the recovery tank, the cost for recovery is increased. The reasons are described as follows. In order to easily remove the plating solution from the object, pure water is stored in the recovery tank so as to recover the plating solution. Therefore, in order to recycle the solution in the recovery tank as a plating solution, it is necessary to concentrate the solution to a predetermined concentration. Therefore, it is necessary to provide a device for concentrating the solution, and the manufacturing cost for concentration is required. Further, when the recovery tank is continuously used, the concentration of the solution in the recovery tank is increased, and the recovering capacity is lowered. Accordingly, it is necessary to periodically adjust the concentration of the solution in the recovery tank.